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Question DetailsAsked on 9/17/2017

I want to put down new carpet but want to make sure the floor is dry enough. I understand I can hire professionals with fancy equipment to measure moisture but are there rules of thumb I can go by instead. I'm just looking for rough range (1 day, 1 week, 1 month, 6 months?)

1 Answer

Just with A/C - I would say about 2-3 days for elevated concrete floor, 3-5 for slab-on-grade, more like 5-10 days if in cool basement. With wood subfloor - depending on how soaked it got, could be 2-3 days or more than a week or more with just A/C running depending on household humidity - in very humid outside conditions could easily be a week or more. If wood over concrete (so concrete underneath is still wet) I would say weeks without getting serious airflow in under the wood if elevated off the concrete - if in direct contact I would say take the wood up because you are pretty much guaranteed to have mold forming in there.

One factor to consider - if wood subfloor stays wet for more than a couple of days you are asking for mold formation, so the thing to do is get a Water and Smoke Damage contractor in to dry it out, or if totally a DIY job soak up everything you can with sponges or mop, then get large (minimum 20") fans to move the air over the wet floor to evaporate it quicker, because the air exchange at the floor is not naturally high. You can get 20" range fans for $20-40 at box stores, or rent larger drying out ones at tool rental places and many home improvement box stores which rent tools and equipment. A large drying-out fan like you can rent can do a normal size room by itself if you can move it around every few hours to dry all surfaces well, would probably take a couple of 20" size box fans. Key is to aim the fans so they cause a circular airflow in the room, aimed a bit so they promote airflow along the walls.

One the wood moisture issue - you can sometimes rent wood moisture meters too (propretty much a joke) costs about $40-60 to buy.

One thing you did not say is about walls - if they flooded, without drying out within a couple of days you will have mold in there - and without removing drywall and insulation you basically cannot dry them out yourself. For uninsulated walls (interiors walls and in some warm area houses exterior wealls too) pros have octopus units with a half dozen or more hoses they stick into holes in the walls to dry them out, but not easy to do yourself unless "flooding" was just in one or two stud bays due to a pipe leak, as opposed to hurricane flooding or such. Usually a major insurance claim.

Generally, a "flooded" house from outside high water levels calls for a pro remediation and pulling off the drywall to about a foot or sometimes more above the flooding limit, replacing all damp/wet insulation (which with some types like shredded jeans and blown-in cellulose can mean to a number of feet above flood level), then drying out the remaining wall components.

Note you also did not address the issue of disinfection - if this was hurricane floodwater, especially if in a city area, it had sewage with it so disinfection before drying out is necessary - usually with a bleach solution or in some cases (like walls) with a disinfectant gas.